Synthesis of crystalline ZSM-23

ABSTRACT

This invention relates to a new form of crystalline material identified as having the structure of ZSM-23, to a new and useful method for synthesizing said crystalline material and to use of said crystalline material prepared in accordance herewith as a catalyst for organic compound, e.g., hydrocarbon compound, conversion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new and useful method for synthesizing a highly useful form of crystalline material identified as having a ZSM-23 structure, the new ZSM-23 synthesized, and use of the crystalline material synthesized in accordance herewith as a catalyst component for organic compound, e.g., hydrocarbon compound, conversion.

More particularly, this invention relates to a method for preparing the crystalline ZSM-23 structure whereby synthesis is facilitated and reproducible and the product exhibits high purity and catalytic utility.

2. Discussion of the Prior Art

ZSM-23 contains one-dimensional pores made up of 10--membered rings. It is shown to be synthesized from reaction mixtures containing pyrrolidine directing agent in U.S. Pat. No. 4,076,842; and diisopropanolamine directing agent in Great Britain Patent Application 2,190,910. U.S. Pat. Nos. 4,490,342; 4,531,012 and 4,619,820 show synthesis of ZSM-23 from reaction mixtures containing "Diquat-7" directing agent. Diquat-7 is a diquaternary ammonium compound having the formula: (CH₃)₃ N⁺ RN⁺ (CH₃)₃, wherein R is a saturated or unsaturated straight chain hydrocarbon group having seven carbon atoms. Diquat-8 is said in U.K. Patent Application 2,202,838 to direct ZSM-23 synthesis.

The above disclosures are incorporated herein by reference as to ZSM-23 and its synthesis.

Various organic directing agents are taught for synthesis of various crystalline materials. For example, U.S. Pat. No. 4,139,600 teaches a method for synthesis of zeolite ZSM-5 from a reaction mixture comprising, as a directing agent, an alkyldiamine. U.S. Pat. No. 4,296,083 claims synthesizing zeolites characterized by a Constraint Index of 1 to 12 and an alumina/silica mole ratio of not greater than 0.083 from a specified reaction mixture containing an organic nitrogen-containing cation provided by an amine identified as being selected from the group consisting of triethylamine, trimethylamine, tripropylamine, ethylenediamine, propanediamine, butanediamine, pentanediamine, hexanediamine, methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, benzylamine, aniline, pyridine, piperidine and pyrrolidine.

Piperidine is disclosed as an organic directing agent for mordenite synthesis by P. A. Jacobs and J. A. Martens, Studies of Surface Science and Catalysis, 33, 12 (1987); and 2-aminopyridine is taught for this purpose in U.S. Pat. No. 4,390,457. Tetra-n-propylammonium salts are taught to be mordenite directing agents in U.S. Pat. Nos. 4,707,345 and 4,788,380.

U.S. Pat. No. 4,151,189 claims a method for synthesizing zeolites ZSM-5, ZSM-12, ZSM-35 and ZSM-38 containing an organic nitrogen cation from a specified reaction mixture containing a primary amine having 2 to 9 carbon atoms as a directing agent. U.S. Pat. No. 4,341,748 shows synthesis of ZSM-5 structure from reaction mixtures comprising ethanol, ZSM-5 seeds, ethanol and seeds, ethanol and ammonium hydroxide, and ethanol, ammonium hydroxide and ZSM-5 seeds. U.S. Pat. No. 4,100,262 teaches synthesis of ZSM-5 from a reaction mixture comprising a tetraalkylammonium source and a tetraureacobalt (II) complex.

Lok et al. (3 Zeolites, 282-291 (1983)) teach numerous organic compounds which act as directing agents for synthesis of various crystalline materials, such as, for example, ZSM-5, ZSM-11, ZSM-12, ZSM-20, ZSM-35, ZSM-48, AlPO₄ -5, AlPO₄ -8, AlPO₄ -20 and others. The article does not show the presently required organic for synthesis of ZSM-23.

The zeolitic composition labeled PSH-3 in U.S. Pat. No. 4,439,409 is synthesized from reaction mixtures containing hexamethyleneimine as directing agent. U.S. Pat. No. 4,954,325 utilizes hexamethyleneimine in another reaction mixture to direct synthesis of MCM-22. That organic is used in U.S. Pat. No. 4,981,663 for synthesis of yet another crystalline structure labelled MCM-35. ZSM-35 is directed by this same compound in U.S. Pat. No. 4,925,548.

Other publications teaching various organic directing agents for synthesis of various crystalline materials include, for example, U.S. Pat. No. 4,592,902, teaching use of an alkyltropinium directing agent, alkyl being of 2 to 5 carbon atoms, for synthesis of ZSM-5; U.S. Pat. No. 4,640,829, teaching use of dibenzyldimethylammonium directing agent for synthesis of ZSM-50; U.S. Pat. No. 4,637,923, teaching use of (CH₃)₂ (C₂ H₅)N⁺ (CH₂)₄ N⁺ (C₂ H₅)(CH₃)₂ directing agent for synthesis of another novel zeolite; U.S. Pat. No. 4,585,747, teaching use of bis (N-methylpyridyl) ethylinium directing agent for synthesis of ZSM-48; U.S. Pat. No. 4,585,746, teaching use of bis (N-methylpyridyl) ethylinium directing agent for synthesis of ZSM-12; U.S. Pat. No. 4,584,286, mentioned above, teaching use of bis(N-methylpyridyl) ethylinium directing agent for synthesis of ZSM-35; U.S. Pat. No. 4,568,654, teaching use of cobalticinium, dimethylpiperidinium, trimethylene bis trimethylammonium or tetramethylpiperazinium directing agents for synthesis of ZSM-51; U.S. Pat. No. 4,559,213, teaching use of DABCO-C₄₋₁₀ -diquat directing agent for synthesis of ZSM-12; U.S. Pat. No. 4,482,531, teaching synthesis of ZSM-12 with a DABCO-C_(n) -diquat, n being 4,5,6 or 10, directing agent; and U.S. Pat. No. 4,539,193, teaching use of bis (dimethylpiperidinium) trimethylene directing agent for synthesis of ZSM-12.

Various diquaternary ammonium compounds have been identified as directing agents for a particular assortment of other crystalline materials. For instance, U.S. Pat. No. 4,665,250 teaches the use of linear diquaternary ammonium compounds of the structure (CH₃)₃ N⁺ (CH₂)_(m) N⁺ (CH₃)₃, m being 5, 6, 8, 9 or 10, for synthesis of ZSM-48.

U.S. Pat. No. 4,623,527 teaches numerous diquaternary ammonium compounds and shows use of (CH₃)₃ N⁺ (CH₂)₇ N⁺ (CH₃)₃ directing agent for synthesis of MCM-10. European Patent Application 377,291 teaches use of Diquat-n, n being 8-12, to direct synthesis of zeolite NU-87. U.S. Pat. No. 4,632,815 teaches numerous diquaternary ammonium compounds and shows use of (CH₃)₃ N⁺ (CH₂)₄ N⁺ (CH₃)₃ to direct synthesis of a Silica-X structure type. U.S. Pat. No. 4,585,639 teaches use of the diquaternary (C₂ H₅)(CH₃)₂ N⁺ (CH₂)₄ or 6 N⁺ (CH₃)₂ (C₂ H₅) as directing agent for synthesis of ZSM-12. Synthesis of ZSM-5 is directed by the diquaternary (alkyl)₃ N⁺ (CH₂)₆ N⁺ (alkyl)₃, alkyl being propyl or butyl, in U.S. Pat. No. 4,585,638.

EPA 42,226 and U.S. Pat. No. 4,537,754 teach existence of numerous diquaternary ammonium compounds, but show use of (CH₃)₃ N⁺ (CH₂)₆ N⁺ (CH₃)₃ as directing agent for synthesis of EU-1. EPA 51,318 teaches use of the same diquaternary for synthesis of TPZ-3. It is noted that EU-1, TPZ-3 and ZSM-50 (synthesized with dibenzyldimethylammonium directing agent) have the same structure.

Applicants know of no prior art method for preparing a crystalline structure identified as ZSM-23 utilizing the present method.

SUMMARY OF THE INVENTION

An economical and reproducible method for preparing a crystalline material identified as ZSM-23 exhibiting high catalytic activity and other valuable properties is provided. The method comprises forming a reaction mixture hydrogel containing sources of alkali metal (M) cations, preferably Na⁺ ; an oxide of trivalent element (X), e.g., aluminum, boron, iron, gallium, indium and mixtures thereof; an oxide of tetravalent element (Y), e.g., silicon, germanium, tin and mixtures thereof; a directing agent (R) of Diquat-12, more particularly described hereinafter; and water, said reaction mixture having a composition in terms of mole ratios, within the following ranges:

    ______________________________________                                         Reactants    Useful      Preferred                                             ______________________________________                                         YO.sub.2 /X.sub.2 O.sub.3                                                                   >60 to 300  >60 to 200                                            H.sub.2 O/YO.sub.2                                                                          35 to 65    40 to 60                                              OH.sup.- /YO.sub.2                                                                          >0.2 to 0.40                                                                               0.23 to 0.35                                          M/YO.sub.2    >0.2 to <0.60                                                                             0.23 to 0.37                                          R/YO.sub.2   0.05 to 0.20                                                                               0.07 to 0.15                                          ______________________________________                                    

The method further comprises maintaining the reaction mixture until crystals of ZSM-23 structure are formed. Reaction conditions required consist of heating the foregoing reaction mixture to a temperature of from greater than about 165° C. to about 200° C. for a period of time of from at least about 80 hours to about 10 days. A more preferred temperature range is from about 170° C. to about 190° C. with the amount of time at a temperature in such range being from about 96 hours to about 8 days. The solid product comprising ZSM-23 crystals is recovered from the reaction medium, as by cooling the whole to room temperature, filtering and water washing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents the X-ray powder diffraction pattern of the product of Example 7, hereinafter presented.

FIG. 2 presents the X-ray powder diffraction pattern of the calcined product of Example 5, hereinafter presented.

EMBODIMENTS

The particular effectiveness of the presently required organic directing agent, i.e., Diquat-12, when compared with other directing agents, such as those identified above, for the present synthesis is believed due to its ability to function as a template in the nucleation and growth of ZSM-23 crystals from the above reaction mixture. This is true even though no predigestion of the gel is required prior to crystallization. This different organic agent functions in this fashion in the reaction mixture having the above described composition and under the above described conditions of temperature and time.

It should be noted that the ratio of components of the reaction mixture required herein are critical to achieve maximum effectiveness. For instance, if the YO_(2/) X₂ O₃ ratio is 60 or below, something other than ZSM-23 crystal will form. As the YO_(2/) X₂ O₃ ratio approaches infinity in the reaction mixture, crystallization of another crystal structure increases. Further, if the OH^(-/) SiO₂ or M/SiO₂ ratios are 0.20 or less, another material is synthesized at the expense of ZSM-23. Still further, for most effective synthesis of ZSM-23 by this method, the reaction temperature should be maintained at greater than about 165° C., i.e., at from greater than about 165° C. to about 200° C.

The synthesis of the present invention is facilitated when the reaction mixture comprises seed crystals, such as those having the structure of ZSM-23. The use of at least 0.01%, preferably about 0.10%, and even more preferably about 1% seed crystals (based on total weight) of crystalline material will be useful.

The reaction mixture composition for the synthesis of ZSM-23 crystals hereby can be prepared utilizing materials which can supply the appropriate oxide. The useful sources of X₂ O₃, e.g., aluminum oxide, iron oxide and/or boron oxide, include, as non-limiting examples, any known form of such oxide, e.g., aluminum oxide or hydroxide, organic or inorganic salt or compound, e.g., alumina, aluminates and borates. The useful sources of YO₂, e.g., silicon oxide, include, as non-limiting examples, known forms of such oxide, e.g., silicic acid or silicon dioxide, alkoxy- or other compounds of silicon, including silica gel and silica hydrosol.

It will be understood that each oxide component utilized in the reaction mixture for this synthesis can be supplied by one or more essential reactants and they can be mixed together in any order. For example, any oxide can be supplied by an aqueous solution. The reaction mixture can be prepared either batchwise or continuously. Crystal size and crystallization time for the product composition comprising the ZSM-23 crystals may vary somewhat with the exact nature of the reaction mixture employed within the above limitations.

The Diquat-12 directing agent for use herein has a formula C₁₈ H₄₂ N₂ ⁺⁺, and may be represented as follows:

    (CH.sub.3).sub.3 N.sup.+ (CH.sub.2).sub.12 N.sup.+ (CH.sub.3).sub.3

The source of the directing agent may be, for example, the halide, e.g., chloride or bromide, salt. Diquat-12 was synthesized for use herein, as follows:

Sixty g (0.18 mole) 1,12-dibromododecane were slurried in 260 mL methanol in a Fisher Porter pressure bottle, chilled in Dry-Ice/isopropanol, evacuated, and 31.5 g (0.53 mole) trimethylamine were run in from an inverted cylinder. The bottle was gradually warmed to room temperature, then heated in a boiling water bath for two hours, cooled, and the solvent and excess amine removed at reduced pressure to yield 81 g (99%) analytically pure material whose ¹³ C NMR confirmed its structure with peaks at 55.9, 70.0, 25.1, 31.5, 31.3, 31.0, and 28.3 ppm in D₂ O vs. 3-(trimethylsilyl) 1-propanesulfonic acid as internal standard. Elemental analysis revealed 47.70% C (48.43% calc.), 9.45% H (7.48% calc.), 5.85% N (6.28% calc.), 35.93% Br (35.80% calc.), and <140 ppm Na.

The ZSM-23 crystal composition prepared hereby has a characteristic X-ray diffraction pattern, including values substantially as set forth in Table 1, hereinafter.

                  TABLE 1                                                          ______________________________________                                         Interplanar d-Spacing, (A)                                                                      Relative Intensity (I/I.sub.o)                                ______________________________________                                         11.2 + 0.23      m                                                             10.1 + 0.20      w                                                             7.87 + 0.15      w                                                             5.59 + 0.10      w                                                             5.44 + 0.10      w                                                             4.90 + 0.10      w                                                             4.53 + 0.10      s                                                             3.90 + 0.08      vs                                                            3.72 + 0.08      vs                                                            3.62 + 0.07      vs                                                            3.54 + 0.07      m                                                             3.44 + 0.07      s                                                             3.36 + 0.07      w                                                             3.16 + 0.07      w                                                             3.05 + 0.06      w                                                             2.99 + 0.06      w                                                             2.85 + 0.06      w                                                             2.54 + 0.05      m                                                             2.47 + 0.05      w                                                             2.40 + 0.05      w                                                             2.34 + 0.05      w                                                             ______________________________________                                    

These X-ray diffraction data were collected with a Scintag theta-theta powder diffraction system, equipped with a graphite diffracted beam monochromator and scintillation counter, using copper K-alpha radiation. The diffraction data were recorded by step-scanning at 0.05 degrees of two-theta, where theta is the Bragg angle, and a counting time of 1 second for each step. The interplanar spacings, d's, were calculated in Angstrom units (A), and the relative intensities of the lines, I/I_(o), where I_(o) is one-hundredth of the intensity of the strongest line, above background, were derived with the use of a profile fitting routine (or second derivative algorithm). The intensities are uncorrected for Lorentz and polarization effects. The relative intensities are given in terms of the symbols vs=very strong (75-100), s=strong (50-74), m=medium (25-49) and w=weak (0-24). It should be understood that diffraction data listed for this sample as single lines may consist of multiple overlapping lines which under certain conditions, such as differences in crystallite sizes or very high experimental resolution or crystallographic change, may appear as resolved or partially resolved lines. Typically, crystallographic changes can include minor changes in unit cell parameters and/or a change in crystal symmetry, without a change in topology of the structure. These minor effects, including changes in relative intensities, can also occur as a result of differences in cation content, framework composition, nature and degree of pore filling, and thermal and/or hydrothermal history.

The crystalline ZSM-23 prepared hereby has a composition involving the molar relationship:

    X.sub.2 O.sub.3 :(y)YO.sub.2

wherein X is a trivalent element, such as aluminum, boron, iron, indium and/or gallium, preferably aluminum; Y is a tetravalent element, such as silicon, tin and/or germanium, preferably silicon; and y is from about 60 to about 300, usually from about 60 to about 200. In the as-synthesized form, the crystalline material has a formula, on an anhydrous basis and in terms of moles of oxides per y moles of YO₂, as follows:

    (0.1 to 1.0)M.sub.2 O:(1.0 to 4.0)R:X.sub.2 O.sub.3 :(y)YO.sub.2

wherein M and R are as defined above. The M and R components are associated with the material as a result of their presence during crystallization, and are easily removed by postcrystallization methods hereinafter more particularly described.

Synthetic ZSM-23 crystals prepared in accordance herewith can be used either in the as-synthesized form, the hydrogen form or another univalent or multivalent cationic form. It can also be used in intimate combination with a hydrogenating component such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or a noble metal such as platinum or palladium where a hydrogenation-dehydrogenation function is to be performed. Such components can be exchanged into the composition, impregnated therein or physically intimately admixed therewith. Such components can be impregnated in or on to the ZSM-23 such as, for example, by, in the case of platinum, treating the material with a platinum metal-containing ion. Suitable platinum compounds for this purpose include chloroplatinic acid, platinous chloride and various compounds containing the platinum amine complex. Combinations of metals and methods for their introduction can also be used.

Synthetic ZSM-23 crystals, when employed either as an adsorbent or as a catalyst in a hydrocarbon conversion process, should be dehydrated at least partially. This can be done by heating to a temperature in the range of from about 65° C. to about 315° C. in an inert atmosphere, such as air, nitrogen, etc., and at atmospheric or subatmospheric pressures for between 1 and 48 hours. Dehydration can be performed at lower temperature merely by placing the zeolite in a vacuum, but a longer time is required to obtain a particular degree of dehydration. The thermal decomposition product of the newly synthesized ZSM-23 can be prepared by heating same at a temperature of from about 200° C. to about 550° C. for from 1 hour to about 48 hours.

The original cations, e.g., alkali metal, of the as-synthesized material can be replaced in accordance with techniques well known in the art, at least in part, by ion exchange with other cations. Preferred replacing cations include metal ions, hydrogen ions, hydrogen precursor, e.g., ammonium, ions and mixtures thereof. Particularly preferred cations are those which render the material catalytically active, especially for certain hydrocarbon conversion reactions. These include hydrogen, rare earth metals and metals of Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB and VIII of the Periodic Table of the Elements, especially gallium, indium and tin.

Typical ion exchange technique would be to contact the synthetic ZSM-23 material with a salt of the desired replacing cation or cations. Examples of such salts include the halides, e.g., chlorides, nitrates and sulfates.

Representative ion exchange techniques are disclosed in a wide variety of patents including U.S. Pat. Nos. 3,140,249; 3,140,251; and 3,140,253.

Following contact with the salt solution of the desired replacing cation, the ZSM-23 is then preferably washed with water and dried at a temperature ranging from 65° C. to about 315° C. and thereafter may be calcined in air or other inert gas at temperatures ranging from about 200° C. to about 550° C. for periods of time ranging from 1 to 48 hours or more to produce a catalytically-active thermal decomposition product thereof.

The crystalline ZSM-23 prepared by the instant invention is formed in a wide variety of particle sizes. Generally speaking, the particles can be in the form of a powder, a granule, or a molded product, such as extrudate having particle size sufficient to pass through a 2 mesh (Tyler) screen and be retained on a 400 mesh (Tyler) screen. In cases where the catalyst is molded, such as by extrusion, the crystalline material can be extruded before drying or dried or partially dried and then extruded.

In the case of many catalysts, it is desired to incorporate the crystals hereby prepared with another material resistant to the temperatures and other conditions employed in certain organic conversion processes. Such matrix materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and/or metal oxides, e.g., alumina, titania and/or zirconia. The latter may be either naturally occurring or in the form of gelatinous precipitates, sols or gels including mixtures of silica and metal oxides. Use of a material in conjunction with the ZSM-23, i.e., combined therewith, which is active, may enhance the conversion and/or selectivity of the catalyst in certain organic conversion processes. Inactive materials suitably serve as diluents to control the amount of conversion in a given process so that products can be obtained economically and orderly without employing other means for controlling the rate or reaction. Frequently, crystalline catalytic materials have been incorporated into naturally occurring clays, e.g., bentonite and kaolin. These materials, i.e., clays, oxides, etc., function, in part, as binders for the catalyst. It is desirable to provide a catalyst having good crush strength because in a petroleum refinery the catalyst is often subjected to rough handling, which tends to break the catalyst down into powder-like materials which cause problems in processing.

Naturally occurring clays which can be composited with the hereby synthesized crystalline material include the montmorillonite and kaolin families which include the subbentonites, and the kaolins commonly known as Dixie, McNamee, Georgia and Florida clays, or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification.

In addition to the foregoing materials, the present crystals can be composited with a porous matrix material such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, as well as ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-zirconia. The matrix can be in the form of a cogel. A mixture of these components could also be used.

The relative proportions of finely divided crystalline material and matrix vary widely with the crystalline material content ranging from about 1 to about 90 percent by weight, and more usually in the range of about 2 to about 50 percent by weight of the composite.

Employing a catalytically active form of the catalyst of this invention which may contain additional hydrogenation components, reforming stocks can be reformed employing a temperature between about 370° C. and about 540° C. The pressure can be between about 100 psig and about 1000 psig, but it is preferably between about 200 psig and about 700 psig. The liquid hourly space velocity is generally between about 0.1 and about 10 hr⁻¹, preferably between about 0.5 and about 4 hr⁻¹, and the hydrogen to hydrocarbon mole ratio is generally between about 1 and about 20, preferably between about 4 and about 12.

The catalyst can also be used for hydroisomerization of normal paraffins, when provided with a hydrogenation component, e.g., platinum. Hydroisomerization is carried out at a temperature between about 90° C. and 375° C., preferably about 145° C. to about 290° C., with a liquid hourly space velocity between about 0.01 and about 2 hr⁻¹, preferably between about 0.25 and about 0.50 hr⁻¹, employing hydrogen such that the hydrogen to hydrocarbon mole ratio is between about 1:1 and about 5:1.

The catalyst can also be used for reducing the pour point of gas oils. This reaction may be conducted at a liquid hourly space velocity between about 10 and about 30 hr⁻¹ and at a temperature between about 400° C. and about 540° C.

Other reactions which can be accomplished employing the catalyst of this invention containing a metal, e.g., platinum, include hydrogenation-dehydrogenation reactions and desulfurization reactions.

Examples 1-10

In order to more fully illustrate the nature of the invention and the manner of practicing same, the following examples are presented.

In these examples, colloidal silica sol (30% SiO₂), a source of alumina, NaOH (50%), the Diquat-12 prepared as indicated above, and deionized water were mixed to form a hydrogel. The source of alumina in Example 9 was aluminum sulfate, i.e., Al₂ (SO₄)₃.sup.. 18H₂ O. Sodium aluminate was the source of alumina in the other examples. When needed to adjust the OH^(-/) SiO₂ molar ratio in an example, sulfuric acid was used.

Crystallizations were conducted for each example in a 300 mL Teflon-lined stainless-steel autoclave equipped with a stirrer. The sealed autoclave for each example was heated at a ramp rate of 2° C./minute to the desired crystallization temperature.

At the conclusion of each reaction, the mixture was allowed to cool, and the product was recovered by filtering and washing with a large amount of distilled deionized water. The washed product was then dried under an infrared heat lamp in a stream of air.

After drying, the product of each example was submitted for X-ray powder diffraction, NMR and chemical analysis. Solution ¹³ C NMR data were obtained on a 200 MHz spectrometer using the 10 mm C/H dual liquids probe. The spectra were measured at 50.18 MHz using 18 Hz spinning, 10 μs (50°) pulses, and a 3 second pulse delay.

Reaction mixture compositions, reaction conditions, and product results are listed in Table 2. Table 3 presents the X-ray diffraction data for the product of Example 7, and Table 4 presents the X-ray data for the product of Example 5 after calcination at 538° C. for 5 hours in air. FIG. 1 shows the X-ray diffraction pattern for the as-synthesized product of Example 7. FIG. 2 shows the X-ray diffraction pattern for the calcined product of Example 5.

The values listed in Table 4 correspond to those peaks which were identified to belong to ZSM-23. This particular sample also contained quartz (SiO₂) and ZSM-12 as secondary phases. In the Table, the strongest peak corresponding to ZSM-23 has been assigned a relative intensity of 100, disregarding the intensities of the secondary impurity phases, and the relative intensities of the other ZSM-23 peaks have been calculated relative to this peak. There are some minor variations between the relative intensities for the present calcined Example 5 product and those listed as standard peak intensities for ZSM-23. These variations are expected by those skilled in this art because of the presence of the secondary phases and their varying contributions to the peak intensities.

                                      TABLE 2                                      __________________________________________________________________________          SiO.sub.2 /                                                                        H.sub.2 O/                                                                         OH.sup.- /                                                                         Na.sup.+ /                                                                         R/ Time                                                                              Temp.                                               Example                                                                             Al.sub.2 O.sub.3                                                                   SiO.sub.2                                                                          SiO.sub.2                                                                          SiO.sub.2                                                                          SiO.sub.2                                                                         (hr)                                                                              (°C.)                                                                       Products                                        __________________________________________________________________________     1    45  60  0.30                                                                               0.34                                                                               0.13                                                                              288                                                                               160 amorphous/                                                                     layered                                         2    60  40  0.30                                                                               0.60                                                                               0.10                                                                              144                                                                               180 mordenite                                       3    90  60  0.20                                                                               0.30                                                                               0.10                                                                              144                                                                               180 amorphous/                                                                     layered                                         4    90  60  0.27                                                                               0.29                                                                               0.10                                                                               72                                                                               180 layered                                         5    90  60  0.27                                                                               0.29                                                                               0.10                                                                              144                                                                               180 ZSM-23 + SiO.sub.2                                                             and ZSM-12                                                                     impurity                                        6    90  60  0.30                                                                               0.32                                                                               0.10                                                                              144                                                                               165 layered                                         7    90  60  0.30                                                                               0.32                                                                               0.10                                                                              144                                                                               180 ZSM-23                                          8    90  60  0.35                                                                               0.37                                                                               0.10                                                                              144                                                                               180 ZSM-23 + modenite                                                              impurity                                        9    177 40  0.25                                                                               0.26                                                                               0.10                                                                               96                                                                               180 ZSM-23 + SiO.sub.2                                                             impurity                                        10   ∞                                                                            40  0.23                                                                               0.23                                                                               0.10                                                                               72                                                                               180 ZSM-48                                          __________________________________________________________________________

                  TABLE 3                                                          ______________________________________                                         Interplanar     Degrees  Relative                                              d-spacing (A)   2-Theta  Intensity                                             ______________________________________                                         11.6390         7.595    5.0                                                   11.3213         7.809    8.2                                                   11.0737         7.984    13.4                                                  10.9277         8.091    16.6                                                  10.6499         8.302    26.3                                                  10.0135         8.831    2.5                                                   9.8166          9.008    18.8                                                  7.8290          11.302   5.4                                                   7.7021          11.489   23.1                                                  6.0051          14.751   2.7                                                   5.5526          15.961   6.6                                                   5.4162          16.366   0.9                                                   5.3792          16.479   4.8                                                   4.8820          18.171   3.4                                                   4.8429          18.319   12.2                                                  4.6931          18.909   3.6                                                   4.6349          19.148   3.2                                                   4.4914          19.766   59.9                                                  4.3996          20.183   19.3                                                  4.2267          21.018   100.0                                                 4.1300          21.516   15.4                                                  3.8740          22.956   93.7                                                  3.7190          23.927   26.8                                                  3.6876          24.134   53.3                                                  3.5979          24.745   56.5                                                  3.5180          25.316   27.9                                                  3.4174          26.074   42.0                                                  3.3303          26.769   97.5                                                  3.1732          28.120   2.7                                                   3.1537          28.297   10.4                                                  3.1344          28.476   1.4                                                   3.0262          29.517   5.7                                                   2.9800          29.985   1.6                                                   2.9660          30.130   3.2                                                   2.8360          31.545   2.9                                                   2.8218          31.709   7.7                                                   2.7962          32.007   1.8                                                   2.7056          33.109   1.6                                                   2.6463          33.873   1.6                                                   2.6304          34.083   2.9                                                   2.5294          35.490   26.1                                                  2.5025          35.884   2.0                                                   2.4650          36.448   7.5                                                   2.4491          36.693   9.1                                                   2.4301          36.990   1.8                                                   2.3930          37.585   2.7                                                   2.3833          37.744   6.1                                                   2.3357          38.543   4.5                                                   2.3293          38.654   2.3                                                   2.3270          38.694   3.4                                                   2.3154          38.895   3.4                                                   ______________________________________                                    

                  TABLE 4                                                          ______________________________________                                         Interplanar     Degrees  Relative                                              d-spacing (A)   2-Theta  Intensity                                             ______________________________________                                         11.1861         7.903    45.9                                                  10.8239         8.168    51.3                                                  9.9628          8.876    41.4                                                  7.7886          11.360   47.3                                                  6.0660          14.602   6.2                                                   5.5986          15.829   10.2                                                  5.4121          16.378   7.1                                                   4.9235          18.016   3.3                                                   4.8741          18.200   9.5                                                   4.5182          19.648   77.0                                                  4.4243          20.069   17.4                                                  4.1475          21.424   9.5                                                   3.8890          22.866   100.0                                                 3.8184          23.295   11.7                                                  3.7304          23.852   38.1                                                  3.7011          24.044   49.6                                                  3.6110          24.653   68.9                                                  3.5250          25.264   40.0                                                  3.4540          25.793   7.6                                                   3.4285          25.988   51.0                                                  3.1255          28.558   1.9                                                   3.0761          29.027   1.7                                                   3.0362          29.417   10.2                                                  2.9781          30.004   1.4                                                   ______________________________________                                    

These examples demonstrate the present invention of synthesizing crystals having the structure of ZSM-23 from the required reaction mixture. When the YO_(2/) X₂ O₃ molar ratio of the reaction mixture was outside the range of from greater than 60 to 300, and the time and/or temperature limitations were not met (Examples 1 and 10), or the M/YO₂ ratio requirement was not met (Example 2), products other than ZSM-23 were formed. An amorphous/layered product was formed in Example 3 when the OH^(-/) YO₂ was not greater than 0.20 as required in the present invention. Example 4 shows that reaction time of less than about 80 hours leads to a product other than ZSM-23. Also, Example 6 demonstrates that ZSM-23 is not synthesized if the reaction temperature is not greater than 165° C.

Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the appended claims. 

What is claimed is:
 1. A method for synthesizing crystalline material exhibiting a characteristic X-ray diffraction pattern including d-spacing maxima values as shown in Table 1, which comprises (i) preparing a mixture capable of forming said material, said mixture comprising sources of alkali or alkaline earth metal (M), an oxide of trivalent element (X), an oxide of tetravalent element (Y), water and directing agent (R) of the formula (CH₃)₃ N⁺ (CH₂)₁₂ N⁺ (CH₃)₃, and having a composition, in terms of mole ratios, within the following ranges:

    ______________________________________                                         YO.sub.2 /X.sub.2 O.sub.3                                                                    >60 to 300                                                       H.sub.2 O/YO.sub.2                                                                           35 to 65                                                         OH.sup.- /YO.sub.2                                                                           >0.20 to 0.40                                                    M/YO.sub.2    >0.20 to <0.60                                                   R/YO.sub.2    0.05 to 0.20                                                     ______________________________________                                    

(ii) maintaining said mixture under sufficient conditions including a temperature of from about 165° C. to about 200° C. for a time of at least about 80 hours until crystals of said material are formed; and (iii) recovering said crystalline material from step (ii), said recovered crystalline material containing said R.
 2. The method of claim 1 wherein said mixture has the following composition ranges:

    ______________________________________                                         YO.sub.2 /X.sub.2 O.sub.3                                                                    >60 to 200                                                       H.sub.2 O/YO.sub.2                                                                           40 to 60                                                         OH.sup.- /YO.sub.2                                                                           0.23 to 0.35                                                     M/YO.sub.2    0.23 to 0.37                                                     R/YO.sub.2    0.07 to 0.15                                                     ______________________________________                                    


3. The method of claim 1 wherein said mixture further comprises seed crystals in sufficient amount to enhance synthesis of said crystalline material.
 4. The method of claim 3 wherein said seed crystals have the structure of ZSM-
 23. 5. The method of claim 1 wherein said X is aluminum, boron, iron, gallium, indium or a mixture thereof, and said Y is silicon, germanium, tin or a mixture thereof.
 6. The method of claim 1 wherein X comprises aluminum and Y comprises silicon.
 7. A mixture capable of forming crystals of ZSM-23 structure upon crystallization, said mixture comprising sources of alkali metal (M), trivalent element (X) oxide selected from the group consisting of oxide of aluminum, boron, iron, gallium, indium and mixtures thereof; tetravalent element (Y) oxide selected from the group consisting of oxide of silicon, germanium, tin and mixtures thereof; water and directing agent (R) of the formula (CH₃)₃ N⁺ (CH₂)₁₂ N⁺ (CH₃)₃, and having a composition, in terms of mole ratios, within the following ranges:

    ______________________________________                                         YO.sub.2 /X.sub.2 O.sub.3                                                                    >60 to 300                                                       H.sub.2 O/YO.sub.2                                                                           35 to 65                                                         OH.sup.- /YO.sub.2                                                                           >0.20 to 0.40                                                    M/YO.sub.2    >0.20 to <0.60                                                   R/YO.sub.2    0.05 to 0.20                                                     ______________________________________                                    


8. The method of claim 1 comprising replacing ions of the crystalline material recovered in step (iii), at least in part, by ion exchange with an ion or a mixture of ions selected from the group consisting of hydrogen and hydrogen precursors, rare earth metals and metals from Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB and VIII of the Periodic Table of Elements.
 9. The method of claim 2 comprising replacing ions of the crystalline material recovered in step (iii), at least in part, by ion exchange with an ion or a mixture of ions selected from the group consisting of hydrogen and hydrogen precursors, rare earth metals and metals from Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB and VIII of the Periodic Table of Elements.
 10. The method of claim 8 wherein said replacing ion is hydrogen or a hydrogen precursor.
 11. The method of claim 9 wherein said replacing ion is hydrogen or a hydrogen precursor.
 12. A method for synthesizing crystalline material exhibiting a characteristic X-ray diffraction pattern including d-spacing maxima values as shown in Table 1, which comprises (i) preparing a mixture capable of forming said material, said mixture comprising sources of alkali or alkaline earth metal (M), an oxide of trivalent element (X), an oxide of tetravalent element (Y), water and directing agent (R) of the formula (CH₃)₃ N⁺ (CH₂)₁₂ N⁺ (CH₃)₃, and having a composition, in terms of mole ratios, within the following ranges:

    ______________________________________                                         YO.sub.2 /X.sub.2 O.sub.3                                                                    >60 to 300                                                       H.sub.2 O/YO.sub.2                                                                           35 to 65                                                         OH.sup.- /YO.sub.2                                                                           >0.20 to 0.40                                                    M/YO.sub.2    >0.20 to <0.60                                                   R/YO.sub.2    0.05 to 0.20                                                     ______________________________________                                    

(ii) maintaining said mixture under sufficient conditions including a temperature of from about 165° C. to about 200° C. for a time of at least about 80 hours until crystals of said material are formed; and (iii) recovering said crystalline material from step (ii), said recovered crystalline material having a formula on an anhydrous basis and in terms of moles of oxides per y moles of YO₂ as follows:

    (0.1 to 1.0)M.sub.2 O:(1.0 to 4.0)R:X.sub.2 O.sub.3 :(y)YO.sub.2

wherein y is from about 60 to about
 300. 